For information specifically on the Royal Navy rank of captain, see Captain (Royal Navy).

Captain is the name most often given in English-speaking navies to the rank corresponding to command of the largest ships. The NATO rank code is OF-5, equivalent to an army full colonel.

The equivalent rank in many navies is Ship-of-the-Line Captain. Other equivalent ranks in other navies notably include Captain of Sea and War or Captain at Sea.

Role

The command of a ship is most often given to the naval rank (equivalent to a commissioned officer between commander (OF-4) and commodore or rear admiral (OF-6)). The Polish Navy is, however, a notable exception naval captain in position of Lieutenant or Captain Lieutenant and OF-5 rank being a "commander" (komandor). The naval rank should not be confused with the army, air force or marine rank of captain, which has a NATO code of OF-2.

Title

Any naval officer below the rank of captain who commands a ship, is addressed as "captain" while aboard that ship, by naval custom. The ship's captain also may be referred to as the Skipper. A naval officer with the rank of captain traveling aboard a vessel he does not command is either never referred to by rank, or in some navies, is addressed as Commodore to avoid confusion with the ship's actual commander. The ship's commander remains in charge of the entire ship. Passengers who would otherwise outrank the ship's commander cannot override the commander in matters of directing the ship's operations.

Historically, throughout the Middle Ages, the Navy was an ad-hoc group of ships contracted for the duration of a given conflict and disbanded thereafter. The ship's Master, who would command the ship during peacetime, would also remain in control of all things nautical during wartime. The Captain was merely the commander of the embarked infantry contingent upon the ship, who with the help of his lieutenants would act as the agent of the king--and hence de facto commander--while the ship was contracted with the Navy. During Tudor times, the title of Captain began to refer to the commander of a ship of the Royal Navy, once that organization became established on an ongoing basis and maintained a standing fleet.

As a matter of etiquette in the U.S. Navy there is only one captain aboard a vessel. If a Marine Corps captain is at the officer's mess, he or she is given the courtesy title of major to be differentiated from the head of the ship.

Commands

Captains with sea commands generally command ships of cruiser size or larger. The more senior the officer, the larger the ship. Commanders of aircraft carriers can be rear admirals, but generally, ship commanders are of captain rank or lower. Also, many captains are either retired or have desk jobs.

<gallery> Image:UK-Navy-OF5.svg|Captain insignia of Royal Navy Image:US Navy O6 insignia.svg|Insignia of a U.S. Navy Captain Image:Navy sleeve Capt(N).png|Captain(N) of the Canadian Forces </gallery>

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